1. Field of the Invention
The present invention relates to a power controlling apparatus provided with a power converting circuit for carrying out bi-directional power conversion between a DC circuit and an AC circuit, and particularly for attempting to lower the generation loss thereof.
In a prior art power controlling apparatus for power conversion between a DC power source and a motor/generator, for example, in Patent Document 1, an overheated state of a diode is detected by a thermistor when operating for power generation, and the power generation is stopped when the overheated state is continued for a specified period of time.
In order to lower a generation loss of a diode, for example, in Patent Document 2, there is a rectification device of an AC power generator, and a circuit in which a switching element is connected in parallel to the diode is disclosed.
Patent Document 1
Japanese Published Unexamined Patent Application No. H10-191691 (Refer to Paragraph Nos. 0025 through 0034)
Patent Document 2
Japanese Published Unexamined Patent Application No. H11-196577 (Refer to FIG. 3 and paragraph Nos. 0017 and 0036)
2. Description of the Prior Art
In the power controlling apparatus shown in Patent Document 1, if the temperature of a diode exceeds a specified threshold for a specified period of time when operating for power generation, it is necessary to stop power generation operation in order to prevent burnout due to overheating. Therefore, there was a problem in that power generation operation accompanying great power cannot be continued for a long period. That is, since the ON-voltage (forward direction voltage) of a diode operating for power generation is high, such a problem occurred, by which a loss in the diode is remarkable.
Also, in Patent Document 2, since a switching element is exclusively used for a power generation operation (rectification operation) although the generation loss of the diode is reduced by connecting the switching element in parallel thereto, such a problem existed, due to which the switching element is not applicable to a bidirectional converting apparatus which is an object of the present invention, that is, an apparatus capable of carrying out bidirectional conversion of an inverter operation for converting DC power to AC power and a rectification (power generation) operation for converting AC power to DC power.
The invention was developed to prevent the above-described problems and shortcomings, and it is therefore an object of the invention to provide a power controlling apparatus, capable of carrying out bidirectional power conversion between a DC circuit and an AC circuit, which inexpensively and simply reduces a generation loss of elements and lowers heat generation thereof.